U.S. Pat. No. 5,957,631 discloses a rotary cutting tool comprising a cutting head releasably coupled to a shank, the cutting head and the shank being bounded by cutting head and shank peripheral surfaces mating in shape and dimensions, and having cutting edges at a front end of the cutting head. The cutting head and the shank are advantageously coupled by a dovetail coupling arrangement, providing secure retention and stable coupling, without relying on other coupling means, such as screws. This greatly simplifies assembly and disassembly of cutting heads to/from the shank. However, when assembled, the cutting head coupling portions fully overlie the shank coupling portions, which may hinder coolant delivery to the cutting edges, and may require formation of coolant passages through the cutting head.
To facilitate desirable cooling and lubrication of the cutting tool's cutting edges, cutting heads having a spade-like shape may be employed, such as disclosed in U.S. Pat. No. 4,744,704, U.S. Pat. No. 6,530,728, or U.S. Pat. No. 6,551,036. Spade-like cutting heads are generally thin, allowing portions of the shank to extend forwardly to a region adjacent the cutting edges, and facilitate cooling fluid delivery thereto. However, because of their reduced thickness, some additional means of clamping, such as screws, may be required, and even then, tangential forces acting on the cutting edges may disadvantageously deform the shank.